Make an Outbound Call

POST

api

Account

{auth_id}

Call

Make an outbound call

curl --request POST \
  --url https://api.vobiz.ai/api/v1/Account/{auth_id}/Call/ \
  --header 'Content-Type: application/json' \
  --header 'X-Auth-ID: <api-key>' \
  --header 'X-Auth-Token: <api-key>' \
  --data '
{
  "from": "14155551234",
  "to": "+919876543210",
  "answer_url": "https://example.com/answer",
  "answer_method": "POST"
}
'

{
  "api_id": "5a9fcfee-3d4c-11ef-bef9-0242ac110005",
  "request_uuid": "5a9fd4a0-3d4c-11ef-bef9-0242ac110005",
  "message": "Call fired"
}

POST https://api.vobiz.ai/api/v1/Account/{auth_id}/Call/

Initiate an outbound call to a PSTN number or a SIP endpoint, and make simultaneous bulk calls.

Authentication required:

X-Auth-ID - Your account Auth ID
X-Auth-Token - Your account Auth Token
Content-Type: application/json

Use < to separate multiple destinations (max 1000). Example: 14157654321<14153464321<sip:john1234@api.vobiz.ai

Required Parameters

Field	Type	Required	Description
`from`	string	Yes	The caller ID phone number in E.164 format (e.g., 14157654321).
`to`	string	Yes	Destination number(s) or SIP URI(s). Use `<` to separate multiple destinations (max 1000). Examples: 14157654321, sip:john1234@api.vobiz.ai
`answer_url`	string	Yes	URL called when the call is answered. Must return valid XML.

Callback Parameters

Field	Type	Required	Description
`answer_method`	string	No	HTTP verb for answer_url. Default is POST.
`ring_url`	string	No	Optional URL notified when the call starts ringing.
`ring_method`	string	No	HTTP verb for ring_url. Default is POST.
`hangup_url`	string	No	Optional URL notified when the call is hung up.
`hangup_method`	string	No	HTTP verb for hangup_url. Default is POST.
`fallback_url`	string	No	Invoked if answer_url fails after 3 retries or 60s timeout.
`fallback_method`	string	No	HTTP verb for fallback_url. Default is POST.

Machine Detection Parameters

For detailed machine detection documentation, see the Machine Detection page.

Field	Type	Required	Description
`machine_detection`	string	No	Detect machine on answer. Values: true, hangup.
`machine_detection_time`	integer	No	Time in ms to detect machine. Default: 5000. Allowed: 2000–10000.
`machine_detection_url`	string	No	Callback URL for asynchronous machine detection.
`machine_detection_method`	string	No	HTTP verb for machine_detection_url. Default: POST.
`machine_detection_maximum_speech_length`	integer	No	Max speech duration in ms. Default: 5000. Allowed: 1000–6000.
`machine_detection_initial_silence`	integer	No	Max silence after answer (ms). Default: 4500. Allowed: 2000–10000.
`machine_detection_maximum_words`	integer	No	Max number of sentences. Default: 3. Allowed: 2–10.
`machine_detection_initial_greeting`	integer	No	Max greeting length (ms). Default: 1500. Allowed: 1000–5000.

Advanced Parameters

Field	Type	Required	Description
`caller_name`	string	No	Sets caller name (up to 50 characters). Defaults to caller’s name.
`send_digits`	string	No	DTMF digits to send after the call connects. Use `w` (0.5s wait) or `W` (1s wait). Example: `1w2W3` or `123@1000` (1000ms tone).
`send_on_preanswer`	boolean	No	If true, sends send_digits during pre-answer. Default: false.
`time_limit`	integer	No	Max duration of call in seconds (after answered). Default: 14400 (4 hours). Calls ≥ 86400s are disconnected at 24h.
`hangup_on_ring`	integer	No	Max duration (in seconds) from start of ringing to hangup.

Request Example

{
  "from": "14155551234",
  "to": "14155555678",
  "answer_url": "https://example.com/answer",
  "answer_method": "POST",
  "ring_timeout": "30",
  "time_limit": "3600",
  "hangup_url": "https://example.com/hangup",
  "hangup_method": "POST",
  "caller_name": "John Doe",
  "machine_detection": "false"
}

Response Example

Success Response (200 OK)

{
  "api_id": "5a9fcfee-3d4c-11ef-bef9-0242ac110005",
  "message": "Call fired",
  "request_uuid": "5a9fd4a0-3d4c-11ef-bef9-0242ac110005"
}

Field	Type	Description
`api_id`	string	Unique identifier for this API request.
`message`	string	Confirmation message. `Call fired` on success.
`request_uuid`	string	Unique identifier for the call. Equivalent to `call_uuid`. For bulk dials, each destination is delivered its own UUID via the callback URLs.

The call_uuid (also referred to as request_uuid) is the unique identifier for the call. Both are equivalent and can be used interchangeably. A 200 response means the call was accepted and queued, not that the callee answered - watch the ring_url and answer_url callbacks for the live state.

Error responses

Status	Meaning	How to handle
`400 Bad Request`	A required field (`from`, `to`, `answer_url`, `answer_method`) is missing or malformed, or `to` exceeds 1000 destinations.	Validate the body before sending. Confirm `to` is E.164 or a valid SIP URI.
`401 Unauthorized`	Missing or incorrect `X-Auth-ID` / `X-Auth-Token`, or a lowercase path (`/account/.../call/`).	Send both auth headers and use the PascalCase path `/Account/{auth_id}/Call/`.
`402 Payment Required`	Account balance is too low to place the call.	Top up the balance, then retry.
`404 Not Found`	The `auth_id` does not exist or the path is wrong.	Verify the `auth_id` and the trailing slash on `/Call/`.
`429 Too Many Requests`	You exceeded your calls-per-second (CPS) or concurrent-call limit.	Back off and retry with jitter; spread bulk dials over time.

Use < (not a comma) to separate bulk destinations. A comma is treated as part of a single destination and the call fails to route.

Parameters Sent to Callback URLs

For every voice call you make and receive, Vobiz sends a status update to your configured callback URLs. Read and store this information for analysis, and use the values to change the flow of ongoing calls.

Parameters Sent to ring_url

Field	Type	Description
`From`	string	Caller ID number used to initiate the call.
`To`	string	The destination being called.
`RequestUUID`	string	Unique identifier for the call request.
`ALegRequestUUID`	string	Identifier for the first leg of the call (multi-leg calls).
`CallUUID`	string	Unique identifier for the call.
`Direction`	string	Direction of the call. Always `"outbound"`.
`Event`	string	Event that triggered this notification. Always `"Ring"`.
`CallStatus`	string	Status of the call. Always `"ringing"`.
`SessionStart`	string	Timestamp when early media started. Format: YYYY-MM-DD HH:mm:ss.sssss UTC.
`STIRAttestation`	string	Attestation details assigned to the call by Vobiz.

Parameters Sent to answer_url and fallback_url

Field	Type	Description
`From`	string	Caller ID number used to initiate the call.
`To`	string	The destination being called.
`CallerName`	string	Caller display name, present when the call originates from a SIP endpoint.
`RequestUUID`	string	Unique identifier for the call request.
`ALegRequestUUID`	string	Identifier for the first leg of the call (multi-leg calls).
`CallUUID`	string	Unique identifier for the call.
`Direction`	string	Direction of the call. Always `"outbound"`.
`ALegUUID`	string	Unique identifier for the A leg of the call.
`Event`	string	Event that triggered this notification. Always `"StartApp"`.
`STIRVerification`	string	Attestation details. Possible values: Verified, Not Verified, Not Applicable.
`CallStatus`	string	Status of the call. Always `"in-progress"`.
`SessionStart`	string	Timestamp when early media started. Format: YYYY-MM-DD HH:mm:ss.sssss UTC.
`STIRAttestation`	string	Attestation details assigned to the call by Vobiz.

Parameters Sent to hangup_url

Field	Type	Description
`From`	string	Caller ID number used to initiate the call.
`To`	string	The destination being called.
`RequestUUID`	string	Unique identifier for the call request.
`ALegRequestUUID`	string	Identifier for the first leg of the call (multi-leg calls).
`CallUUID`	string	Unique identifier for the call.
`Direction`	string	Direction of the call. Always `"outbound"`.
`ALegUUID`	string	Unique identifier for the A leg of the call.
`Event`	string	Event that triggered this notification. Always `"Hangup"`.
`stir_verification`	string	Attestation details. Possible values: Verified, Not Verified, Not Applicable.
`CallStatus`	string	Status of the call. Always `"completed"`.
`StartTime`	string	Timestamp when the call was initiated. Format: yyyy-MM-dd HH:mm:ss (local time).
`AnswerTime`	string	Timestamp when the call was answered. Format: yyyy-MM-dd HH:mm:ss (local time).
`SessionStart`	string	Timestamp when early media started. Format: YYYY-MM-DD HH:mm:ss.sssss UTC.
`EndTime`	string	Timestamp when the call ended. Format: yyyy-MM-dd HH:mm:ss (local time).
`STIRAttestation`	string	Attestation details assigned to the call by Vobiz.

Authorizations

X-Auth-ID

string

header

required

Your Vobiz account Auth ID

X-Auth-Token

string

header

required

Your Vobiz account Auth Token

Path Parameters

auth_id

string

required

Your account Auth ID

Example:

"MA_XXXXXX"

Body

application/json

from

string

required

string

required

answer_url

string

required

answer_method

string

required

Response

200 - application/json

Call initiated

api_id

string

required

message

string

required

request_uuid

string

required

The Call Object

Machine Detection

Make an outbound call

curl --request POST \
  --url https://api.vobiz.ai/api/v1/Account/{auth_id}/Call/ \
  --header 'Content-Type: application/json' \
  --header 'X-Auth-ID: <api-key>' \
  --header 'X-Auth-Token: <api-key>' \
  --data '
{
  "from": "14155551234",
  "to": "+919876543210",
  "answer_url": "https://example.com/answer",
  "answer_method": "POST"
}
'

{
  "api_id": "5a9fcfee-3d4c-11ef-bef9-0242ac110005",
  "request_uuid": "5a9fd4a0-3d4c-11ef-bef9-0242ac110005",
  "message": "Call fired"
}

​Required Parameters

​Callback Parameters

​Machine Detection Parameters

​Advanced Parameters

​Request Example

​Response Example

​Error responses

​Parameters Sent to Callback URLs

​Parameters Sent to ring_url

​Parameters Sent to answer_url and fallback_url

​Parameters Sent to hangup_url

Authorizations

Path Parameters

Body

Response

Required Parameters

Callback Parameters

Machine Detection Parameters

Advanced Parameters

Request Example

Response Example

Error responses

Parameters Sent to Callback URLs

Parameters Sent to ring_url

Parameters Sent to answer_url and fallback_url

Parameters Sent to hangup_url